Method of and means for regulating the fuel feed of internal combustion engines



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FUEL

NUMBER L 0F RE VOL UTIOA/s/m/'n '7] Xi' J Dec.. 22, 1936. p. FlLEHR2,965,272

D MEANS METHOD OF AN FOR BEGULATING THE FUEL FEED OF INTERNAL COMBUSTIONENGINES Filed Deo. l5, 193

5 3 Sheets-Sheet 2 Dec. 22, 1936. p, FILEHR 2,065,272

METHOD OF AND MEANSFOR REGULATING THE FUEL FEED OF INTERNAL COMBUSTIONENGINES Filed Dec. 3 Sheets-Sheet 3 lvm'rnon or nun ivmaNs ron nno'rnso:ma rom. rnnn or manner. ne.

THN ENGHNES I Paul Filehr, Massei-K, Geny Application December l5, i933,Serial No. 702,589

ym Ge im t December ll'i, i932 o o (on. icas-reci Applications were nledin .nar on Decemof the engine, the present invention aims .at ber 1'?,1932 and February 16, 1933. eliminating the waste of fuel due to theemploy- The present invention relates to a method of ment of a, constantfeedat widely varying speeds,

and means fOr regulating the fuel feed moli inthis aim being attained bymaintaining at prac- 5 ternal combustion engines of the fuel injectionideally au' speeds ofthe engine substantially the 5l or Diesel type. isame proportion of an' and fuel in the combus- It has been found thatwith most Diesel engines tion space,

the amount of `fresh air .which reaches the com- The reduction of thefuel feed is, according buStiOrl Spee 0f the engine, commences to detothe invention, obtained by devices which rel@ crease at a certain speedof the engine and that .spond directly to the pressure existing in the5'@ engine and thereby a reduction of the speed of .ment for carryingout the inventionafterwards it decreases further gradually and fuelsupply conduit, said pressure'depending on progressively during thefurther increase of speed the speed of the engine and directly on thespeed ci the engine. With the engine Working under of the fuel pump. Theinvention does not use full 10ml that iS developing Substantially illeany mechanical devices, such as centrifugal regui5 maximum torque, itthe4 amount of fresh air lators, directly responsive tothe speed of the15 reachingthe combustion space of the engine at engine and so arrangedas to reduce the fuel lower speeds was just suiicient to ensure asatfeed at increasing speed. isfactory combustion of the normal amountof The invention is preferably carried out by causfllel injected percycle.- the dimculty arises that ing a fuel pump to deliver a constantamount this normal amount of fuel will not ilnd within o fue] into theconduit leading to the fuel 20 the combustion chamber the requiredamount o nozzle, and causing a portion of this amount fresh air.' lt isthe object of the invention to to overflow and be returned to the pumpeither obviatethis diolilty and With this Object in directly or througha by-pass. Overow Valves, view the invention consists in regulating thefuel throttling points and combinations of overflow feed Oi the Dieselengine Werking under full load, valves and throttling devices may beused for 25 that is developing Substantially its mammum this purpose,and it is particularly pointed out tortille in Slleh a manner ,thatcommencing at that various arrangements are known in which a certainspeed oi the engine at which the amount a portion oi the fuel deliveredby the fuel pump of fresh air reaching the combustion space begins is ateach stroke allowed to overow and return to decrease, the fuel feed,that is the amount to the pump and that no claim is made to the oi fuelinjected per cycle, is reduced inproporuse fof such devicesandarrangements per se,

tion so that the actual proportion oi iuel and vexcept as a means forgradually reducing the air in` the combustible mixture is maintainedfuel feed within a wide'range of speeds and lfor during a very widerange oi speeds, wt the, the object above mentioned.

engine is working under ay full load, that -is dee invention isillustrated in the accompanyveloping substantially its marimumA torque.It ing drawings.

will be understood that this reduction of the i is a diagram showing thefuel supply as fuel feed iS gradual and progressive and 1S mainaiimction of the speed or number of revolutions vtained lduring thenormal `operation oi the en- @ff ehelemgine,`

,w gine. The reduction of the fuel feed is not such Fig, 2 showsdiagrammatieany one arrange- 40 as to have any appreciable affect uponthe speed ment for carrying out the invention, of the enginev and is notintended to interfere am 3 shows diagrammaticauy a, second arwith orcontrol the speed of the engine. Various rangement foi. carrying out theinvention. methods have been proposed for controlling or Fig. 3a shows mlarger scale a dtail of Fig. 3

reducing the speed of the engine by controlling hr 45 l or reducing thefuel feed, but itis a charactertlemfll oggsmigglgal; ivrihighdghaseistic feature of all such methods that the reduc- Valvl tion'of the fuelfeed produces immediately a sub-` v's'ta'ntialreduction of the powerdeveloped by the Fi@ 4 Shows dagrammatcanya third arrange' the engine,and that the reduction of the speed Flu. shows diagrammatically anarrangement .offthe engine then produces an increased feed, in which e.plurality of overow means is used. .':sd that van equilibrium is reachedat a certain Fig. ii shows an arrangement in which a plural- 'f-s'peefof the .enginei- Whilst the known method ity oi' throttle means isused.

11555' aimed latfmaintainin'e or controlling the speed Fig. 'l shows anarrangement in which a com- 55 lutlons of the engine is say 400, bedouble the consumption' at the speed corresponding to 200 revolutionsper minute. This is the normal fuel consumption curve of an ordinaryDiesel engine. The chain dotted line II indicates a different fuelconsumption curve which starts at a curtain number of revolutions n andcorresponds to a fuel feed which is smaller. It is the object of theinvention to obtain a fuel consumption curve which, starting at acertain point of the normal curve or straight line I, will lie below theline I. It will be understood that the curves I and II are given only byway of illustration, the essen? tial feature being the fact that curve1I is below curve I and does not show any abrupt change. Moreover, thecurve II corresponds to a very wide range of speeds with which theengine is to run.

In the arrangement according to Fig. 2 a fuel pump I of usualconstruction, which is positively driven by a Diesel engine with aconstant stroke, so that the velocity of discharge of the pump variesdirectly with the engine speed, supplies fluid received from a duct 2via a duct 3 to a fuel injection nozzle 4 of ordinary construction,which is mounted upon a cylinder not shown in the drawings. At a pointof the delivery duct 3 is branched off an overflow duct 5 which leadsback to the fuel reservoir (not shown) or to the admission duct 2 of thefuel pump I. When the speed of the engine is below n, the overflow ductis closed by 'a non-return valve 6 loaded by a spring 'I. The springpressure is so chosen that the valve 6 will open only at a certainpressure in the delivery duct, and will thereby reduce the amount offuel reaching the nozzle 4. This arrangement may be modified oramplified by providing besides the one overflow duct 5 a plurality ofsuch overflow ducts, the non-return valves 6 of which are normally heldclosed by springs, the pressures of the springs being `so chosen thatwhen the pressure in the delivery duct 3 increases, an increased amountof fuel will be tapped and caused to overflow from the delivery duct. Inthis manner any desired form of curve II (Fig. 1) may be obtained.

The, arrangement according to Fig. 3 differs from the arrangement shownin Fig. 2 in that the point at which the main fuel supply is tapped, isarranged directly at the fuel pump. For this purpose there is mountedupon the pump casing I a three-part casing 8, 8', 8, which is providedwith bores leading to the main fuel delivery duct 3' by which the fuelis delivered. From part 8 of the casing is branched off an overflow duct5', which is maintained in the closed position by a non-return valve 6loaded by a spring 'I. The tubes containing the ducts 3' and 5 are xedto their respective casings by means of screw caps which engage theusual connection cones welded to the ends of the tubes, whereby a tightaint is obtained. This arrangement, moreover, differs from thepreviously described arrangement in that a throttling device isprovided. This throttling device comprises a cylindrical plunger 9 whichserves for reducing the cross section of the delivery duct of the pumpand is movable within a cylindrical bore I0' of a member III insertedinto the casing. In the construction shown the plunger 9 acts also as adelivery valve.4 It is controlled by a spring II. plunger 9 and the boreI0' of the member I0 are so dimensioned as to leave a clearance of thesize required for obtaining a throttling action. This arrangement workssubstantially in the same manner as the previously described arrangementof Fig. 2, with the difference however that by the intel-position of thethrottling device in the 'I'he diameter of the delivery duct 3', thepressure which reaches the fuel discharge nozzle and the duct betweenthe pump and the nozzle is damped, which is an advantage in view of thegreat sensitiveness of the discharge nozzle.

It may he pointed out that the plunger 9 exerts a pumping action uponthe delivery duct 3', so that the portion of the duct lying posterior tothe plunger and leading to the fuel nozzle 4, is sucked empty after eachdelivery stroke, where- I-by this portion of the duct is relieved ofpressure. If required, the throttling device may be arranged at anysuitable point of the delivery duct or even at the fuel nozzle itself.-In the latter case the throttling device shown in Fig. 3 may besuitably modified. Moreover, the plunger 9 may be combined with thenon-return valve I2 of the fuel pump to make a single unit, so that theplunger is constituted by the eiitended stem of the valve. Thisarrangement is shown in Fig. 3b, the plunger being designated by thenumeral 9 and the delivery valve by the numeral I2.

It may also be pointed out that besides the throttling of the fuel bythe plunger 9 or 9', there occurs also some compression of the fuel infront of or anterior lto the plunger 9 in the working space of the fuelpump, whereby a certain amount of fuel is stored during the compressionstroke, this stored fuel quantity being then` returned after thetermination of the delivery stroke to the suction space of the pump.

Fig. 3a shows on a larger scale the throttling device of Fig. 3. Theplunger 9 is shown in its middle position, and is indicated by dottedlines and arrows; the movement of the plunger 9 is limited both in theupward and downward direction. A stationary member limiting the-upwardmovement of the plunger 9 contains ports leading to a bore in part 8".When the speed of the fuel pump increases, the amount of fuel passingthrough the annular space between-the plunger 9 and the member I0 willdecrease. Also in the arrangement according to Fig. 3 several overflowducts may be used which come into action one after the other when thepressure in the delivery duct increases with the speed of the engine.

In the arrangement according to Fig. 4, a store space is associated withthe delivery end of the fuel pump, which is closed against the delivery'end of the pump by a spring loaded piston exposed to the deliverypressure of the pump. This space is utilized for storing a portion ofthe fuel delivered by the pump, whichis then returned back into thesuction space of the pump. a indicates the delivery space of the pump, bthe suction space, c the fuel delivery duct, the whole pump beingdesignated by the letter A. d indicates the store space and e indicatesa plunger provided with a fiange upon which latter acts a spring f, theother end of the spring bearing upon a set screw g which serves forregulating the force of the loading spring. Between the suction spaceband a space h provided in the rear of the movable plunger e, there is acommunication duct i. The pump piston lc is provided with a longitudinalgroovec and a lateral groove lc" through which fuel can pass in aoertain position ofthe piston It via lateral bores l from the storespace d into the space b during the return stroke of the piston.

The operation of this arrangement is such that with increasing speed ofthe engine and consequently with increasing pressure in the delivery enda of the pump, the plunger e is displaced against the action of thespring f so as to increase the volume of the space d until the pressurein the space a and the force of the spring f again During the deliverystroke balance each other. a portion of the fuel is stored in the spaced, and after the termination of the delivery stroke the stored amount offuel returns to the suction space b of the pump via grooves k', lc" andthe bores l, the spring f at the same time forcing the plunger e backinto lits initial position. Oil leak ing along the piston e intothespace h likewise returns through the duct i back into the suction spaceb. Y

This arrangement is distinguished by very compact construction and greataccessibility. After loosening the set screw all the important parts ofthe device may be readily taken out, Whilst the other parts which do notrequire attention remain undisturbed in their positions.

Fig.. shows diagrammatically an arrangement in which a pluralityvofoverflow valves is used. In the delivery duct 3 leading from the pump ito the fuel nozzle 4 is interposed a chamber i3 which communicatesv witha plurality of overflow valves, 6', 6", 6"', the springs l', i", l'" ofwhich are of different strengths and are so chosen that the valves willrespond at dierent pressures in the delivery conduit, whereby agradually increasing quantity of fuel will be allowed to escape by theoverflow duct 5. The number of overflow valves depends upon theparticular condtions.Y

Fig. 6 shows diagrammatically an arrangement in which a plurality ofthrottle points is used. A chamber 4 is interposed in the delivery duct3 and communicates with the duct through a plurality of throttlingdevices i5', l5", iS'", similar to those shown in Figs. 3, 3a and 3b.The plungers used in these throttling devices have different crosssectional passage areas, so that they will come into actionprogressively. It may be pointed out that as the fuel is capable ofbeing compressed at the very high pressures occurring, it is notnecessary to provide in this case separate overflow means, as with thespace It anterior to the throttling devices I5', I5", ISV being suitablydimensioned, the delivery duct itself together with that space i4 willact as a fuel store. The fuel is then compressed during the deliverystroke and is returned partly during the suction stroke of the pump.

Fig. 'l shows a combination of a. plurality of overflow valves and aplurality of throttling devices. In this case a space i6 is interposedin the4 delivery duct 3. This space I6 communicates with a plurality ofoverflow valves 6', 6" loaded by springs 'I' and i" of differentstrengths and therefore coming into action at different pressures andspeeds. The space IB also communicates with a number of throttlingdevices it', is" having dinerent cross sectional areas.

I claim:

l. The method of controlling the delivery from.

a reciprocating fuel pump through a feed line to an internal combustionengine at full-cad operation over a wide range of speeds, comprisingoperating the pump cyclically with a constant stroke, and bypassing aportion of the fuel from the feed line proportional to the decrease inthe air volumetric eiciency of the engine at the higher' speeds tocompensate for the decrease in the air charge and thereby maintain thefuel-air ratio constant over the entire range of speeds.

2. The method of controlling the delivery from a reciprocating fuel pumpthrough a lfeed line to a'n internal combustion engine at full-loadoperation over a wide range of speeds, comprising operating the pumpcyclically with a constant stroke, by-passing a portion of the fuel fromthe feed line afterthe pressure in the fuel line has reached 'apredetermined pressure, 'and also throttling the flow of fuel throughthe feed line so that the flow of fuel to the engine is proportional tothe decreased volumetric efficiency of the engine at the higher speedsto compensate for the decrease in the air charge and thereby maintainthe fuel-air ratio substantially constant over the entire range ofspeeds. 4

3. The method o f controlling the delivery of fuel to an internalcombustion engine to maintain a substantially constant ratio of air andfuel in the combustion chamber during the whole range of speeds,comprising proportionally increasing the'delivery pressure of the fuelto' a feed line as the speed of the engine increases, and gradually andproportionally increasing said pressure to the feed line over thepressure from the line to the engine after a predetermined speed hasbeen reached proportional to the decrease in the air volumetric eciencyof the engine at higher speeds to compensate for the .decrease in theair charge and thereby maintain the fuel-air ratio substantiallyconstant over the entire range of speeds.

4. The method according to claim 3, further characterized in that theexcess portion ofthe fuel fed to the feed line is by-passed from the ifuel feed line.

5. The method according to claim 3, further characterized in that theexcess portion of the fuel fed to the feed line is throttled.

6. The method of controlling the delivery from a reciprocating fuel pumpthrough a feed line'to a Diesel engine driving a car at full loadoperation over a wide range of speeds, comprising operating the pumpcyclicallylwith a constant stroke and gradually increasing the pressurein the feed line beyond the pump as the speed increases over thepressure from the line to the engine after a predetermined speed hasbeen reached and in proportion to the decrease in the air volumetricefficiency of the engine to compensate ior the decrease in the aircharge and thereby maintain the fuel-air ratio constant over the entirerange of speeds, said proportional vincrease of pressure in the feedline beyond the' occurring with the increase of the speed of thepumpPAUL FILEHR.

